In recent years, from the standpoint of saving resources and energy, a photocurable resin capable of being cured by light energy such as ultraviolet ray or electron beam is being widely used in the field of printing, coating material and adhesive.
Particularly, in view of productivity, a radical polymerizable•curable resin capable of being cured by ultraviolet ray has been suitably used for the preparation of an etching resist for forming a circuit used in the field of electronic device, a solder resist for protecting a circuit board over a long period of time, a color filter resist for producing individual picture elements of a color filter, or a black matrix resist used in a color filter for dividing respective picture elements and enhancing the contrast.
Examples of such a resin include an epoxy acrylate resin described in Polyester Jushi Handbook (Polyester Resin Handbook), pp. 353-355, Nikkan Kogyo Shinbun Sha (1988), a resin obtained by adding an acrylic acid to a glycidyl methacrylate copolymer described in Japanese Unexamined Patent Publication (Kokai) No. 2001-89553 and then adding a polybasic acid anhydride to the produced hydroxyl group, and a resin obtained by adding a (meth)acrylate compound having an epoxy group to a carboxyl group in the side chain of an acryl-based or styrene-based copolymer described in Kokai Nos. 10-253815 and 10-253816.
However, these resins have a problem in that since the radical polymerizable group is a (meth)acryloyl group, the coating film surface is susceptible to radical polymerization inhibition by oxygen and liable to remain sticky and a sufficiently high photosensitivity cannot be obtained.
In order to solve this problem, a method of adding a photo-radical polymerization initiator in a large amount is generally employed, but this has a problem such that depending on the kind of the photo-radical polymerization initiator, a precipitate originated in the photo-radical polymerization initiator is generated in an alkali developing tank to contaminate the alkali developing tank, or the remaining photo-radical polymerization initiator sublimates at the post-curing of the resist to contaminate a heating furnace or an exhaust duct.
In the present invention, the “(meth)acryl” means “methacryl” and/or “acryl”. The same applies to the “(meth)acryloyl” and the like.
With respect to the method for preventing the polymerization inhibition by oxygen, a method of performing the curing and crosslinking by using a thiyl radical which is less susceptible to inhibition by oxygen, for example, a method of adding a polyfunctional thiol (Kokai Nos. 10-253815, 10-253816 and 2000-249822), has been studied. However, this method is disadvantageous in that a mercapto group and a (meth)acryloyl group are reacted by the Michel addition during storage and therefore, the storage stability is bad.
Also, introduction or the like of an allyl ether group are being attempted. For example, in Japanese Examined Patent Publication (Kokoku) No. 1-51487, a trimethylolpropane diallylether reactant of phthalic anhydride and methacrylic acid are reacted with an epoxy resin to introduce an allyl group and thereby avoid the polymerization inhibition by oxygen. However, the allyl ether group is poor in the radial polymerizability and this method is insufficient in view of the polymerization rate.
Under these circumstances, a curable polymer compound improved in the radical polymerization inhibition by oxygen, and a radical polymerizable•curable composition containing the compound are being demanded.
An object of the present invention is to solve those problems and provide a novel polymer compound extremely insusceptible to polymerization inhibition by oxygen and particularly, curable by light. The object of the present invention includes providing a production process of the radical polymerizable resin and a radical polymerizable•curable composition using the radical polymerizable resin.
As result of intensive investigations to attain the above-described object, the present inventors have found that when a polymer compound having an epoxy group, particularly, a novel polymer compound obtained by using a (meth)acrylic acid ester copolymer having an epoxy group, a fumaric acid monoester having an allyl group and depending on the case, further a (meth)acrylic acid as raw materials and reacting these, is used, a radical polymerizable•curable composition insusceptible to polymerization inhibition by oxygen and particularly, capable of being swiftly cured by light can be provided. The present invention has been accomplished based on this finding.